Strikes planned for the Black Friday play and the run-up to Christmas look apt to spell up aft talks betwixt Royal Mail and the Communication Workers Union (CWU) ended without agreement.
Royal Mail said it had made its "best and last offer" and accused the national of "holding Christmas to ransom".
The CWU has not commented connected the revised offer
Fresh strikes are scheduled for Thursday and Friday.
If nary statement is made, further stoppages are planned for the 30 November and 1 December - conscionable 2 days aft Cyber Monday, 1 of the busiest online buying days - and connected six days successful December, including Christmas Eve.
The long-running quality revolves astir pay, jobs and conditions. The CWU has said plans to alteration Sunday moving and different moving arrangements amounted to the "Uberisation" of the service.
The institution said successful a connection that it had offered unit a 9% wage emergence implicit 18 months, was committing to marque Sunday moving voluntary, and would marque nary compulsory redundancies earlier March adjacent year.
"We privation to scope a deal, but clip is moving retired for the CWU to alteration their presumption and debar further damaging onslaught action," said Royal Mail's main executive, Simon Thompson.
Royal Mail said strikes had already outgo the steadfast much than £100m and that the wage connection whitethorn request to beryllium withdrawn if determination is "further deterioration successful the company's fiscal presumption caused by concern action".
"In a materially loss-making company, with each further time of onslaught enactment we are facing the hard prime of astir whether we walk our wealth connected wage and protecting jobs, oregon connected the outgo of strikes," Mr Thompson said.
The CWU represents 115,000 workers astatine Royal Mail. Last period they rejected a 7% wage connection implicit 2 years.